SU775621A1 - Rate-of-flow meter - Google Patents

Description

one

The invention relates to instrument engineering and is intended to measure the flow of liquid media.

A flow meter is known, which contains a constriction device, a U-shaped pipe-5 ku, valves that communicate a tube with the atmosphere and the medium under investigation, level sensors and a measuring device 1 j

The disadvantages of this flow meter 10 include the need to make measurements on two levels and a tube, low measurement accuracy due to large fluctuations of zero levels in the tube when the static pressure 15 varies, the medium to be measured, temperature, etc.

The closest technical solution to the invention is a flow meter containing a constriction device, tubes with level sensors, an automatic preload device and a transducer.

The flow rate is determined by the difference in levels in the tubes. Measurement of the level difference 25, the initial values of which vary with the changing external conditions (atmospheric pressure, temperature, etc.), does not provide a highly accurate flow measurement. thirty

In addition, the automatic pressure device, made in the specified flow meter as an additional tube connected in gas space to the two Main tubes, does not allow monitoring the flow rate in a wide range and is difficult to adjust when changing from one measurement range to another. The drawback of the device is also low measurement accuracy when monitoring liquids with variable density, since the liquid in the tubes does not exchange with the liquid in the main pipeline.

The purpose of the invention is to improve the measurement accuracy.

The goal is achieved by the fact that in the flow meter containing the constriction device, tubes with level sensors, a transducer and an automatic preload device are the last. made in the form of Ks1mery with gas release and gas inlet valves, -blocked with one of the level sensors, the second of them is connected to the converter, and at the chamber output a generator of pneumatic pulses is connected through the choke.

The flow meter diagram is shown in the drawing.

The flow meter includes a constriction device 1, a manometric tube 2 with a photoelectric sensor 3, a manometric tube 4 with a bellows, the hard center of which is connected to another photoelectric sensor 5, an automatic preload device, which is a chamber 6 with valves 7 and 8 for inlet supply and gas release, choke 9, converter 10 for supplying a signal to a recording, indicating, signaling or regulating device, generator 11 of air pulses, made, for example, in the form connected to the bands tube 2, whose actuator periodically compresses and expands the flutes, changing the internal volume.

Works flow meter as follows.

When fluid flows through the restriction device 1, pressure P and Pj are established at the inlet of the tubes 2 and 4, the difference between which is proportional to the flow rate

Q - KV,

g

Where

- the density of the liquid

coefficient of proportionality.

The pressures P and P are balanced by the pressure of the gas cavity of the tubes 2, 4 and the pressure, respectively, of the liquid column in the tube 2 -РОН and in the tube 4 -Pg-Hr ,. those.

, P2 Po PeH2.

The level On in the tube 4, corresponding to the position of the rigid center of the bellows installed at its end, is kept constant by changing the pressure of the PO in the ash cavity. When the level H deviates, the hard center of the bellows moves, causing the sensor 5 to trip. On the signal from sensor 5 one or another valve 7 or 8 opens, changing the pressure in the chamber of the beating tube 2 until the H2 level is equal to the set one. As a result of the stabilization of the level of H2. In tube 2, the fluid level will automatically be established. M proportional to consumption

at.

.covi.t

The signal from the sensor 3, which controls the HI level, is fed to the converter 10 and further, depending on the purpose of the measurement, to a recording, signaling or regulating device.

In order for the density of the fluid in tubes 2 and 4 not to differ from the density of the fluid flowing through the restriction device, a periodic exchange of fluid in the tubes is performed. This is achieved by means of a generator 11 pneumatic pulses due to periodic compression and paaia and bellows. When the bellows is compressed, the air in the gas cavity is compressed, displacing fluid from the tubes 2 and 4 into the main pipeline. Since the displacement of fluid in tube 2 requires more pressure than in tube 4, a throttle 9 is installed at the outlet of chamber b, reducing pressure in tube 4 with a pressure jump in tube 2. When the pneumatic pulse is removed (return of the bellows to its original position), the liquid flows in the tubes to the levels of H and Hj. proportional to consumption. In order to avoid false alarms, the measurement circuit and the control circuit of the automatic preload device are blocked with a pneumatic pulse generator.

As a level sensor, various level gauges can be used depending on the properties of the studied medium.

Claims (2)

1.Raskhodmar, containing a restriction device installed in the pipeline, tubes with level sensors, automatic preload device and a converter, characterized in that, in order to improve the measurement accuracy, the automatic preload device is designed as a chamber with gas inlet and outlet valves interlocked with one of the level sensors, the second one is connected to the converter. 2. A flow meter according to claim 1, characterized in that, in order to reduce the error from the density change, a generator of pneumatic pulses connected to the tubes and a choke installed between them are inserted, the generator of pneumatic pulses connected to the converter and to the automatic pressing device. Sources of information taken into account in the examination 1. PP Kremlin. Flow meters and quantity counters, l., Mashinostroenie, 1975, p. 174-175. 2. USSR author's certificate if 163383, cl. G 01 I-1/37, 1964 (prototype).